Cold beverages, such as soft drinks, beer, wine coolers, etc. are commonly displayed in convenience stores, supermarkets and other retail establishments in refrigerated merchandisers for self-service purchase by customers. Conventional merchandisers of this type conventionally comprise a refrigerated, insulated enclosure defining a refrigerated product display cabinet and having one or more glass doors. The beverage product, typically in cans or bottles, single or in six-packs, is stored on shelves within the refrigerated display cabinet. To purchase a beverage, the customer opens one of the doors and reaches into the refrigerated cabinet to retrieve the desired product from the shelf.
Beverage merchandisers of this type necessarily include a refrigeration system for providing the cooled environment within the refrigerated display cabinet. Such refrigeration systems include an evaporator housed within the insulated enclosure defining the refrigerated display cabinet and a condenser and compressor housed in a compartment separate from and exteriorly of the insulated enclosure. Cold liquid refrigerant is circulated through the evaporator to cool the air within the refrigerated display cabinet. As a result of heat transfer between the air and the refrigerant passing in heat exchange relationship in the evaporator, the liquid refrigerant evaporates and leaves the evaporator as a vapor. The vapor phase refrigerant is then compressed in the compressor to a high pressure, as well as being heated to a higher temperature as a result of the compression process. The hot, high pressure vapor is then circulated through the condenser wherein in passes in heat exchange relationship with ambient air drawn or blown across through the condenser by a fan disposed in operative association with the condenser. As a result, the refrigerant is cooled and condensed back to the liquid phase and then passed through an expansion device which reduces both the pressure and the temperature of the liquid refrigerant before it is circulated back to the evaporator.
In conventional practice, the condenser comprises a plurality of tubes with fins extending across the flow path of the ambient air stream being drawn or blown through the condenser. A fan, disposed in operative association with the condenser, passes ambient air from the local environment through the condenser. U.S. Pat. No. 3,462,966 discloses a refrigerated glass door merchandiser having a condenser with staggered rows of finned tubes and an associated fan disposed upstream of the condenser that blows air across the condenser tubes. U.S. Pat. No. 4,977,754 discloses a refrigerated glass door merchandiser having a condenser with in-line finned tube rows and an associated fan disposed downstream of the condenser that draws air across the condenser tubes. A problem associated with conventional condensers is that over time dust, grease and other matter carried in the ambient air passing through the condenser collects on the condenser tubes. This air side fouling is problematic in that as the dust and other matter build up on the outside of the condenser tubes, heat transfer between refrigerant flowing through the tubes and the ambient air passing over the tubes decreases thereby degrading overall condenser performance.